JPH0649648A - Plasma cvd device - Google Patents

Abstract

PURPOSE:To prevent the impingement of ion on a substrate in the sheath region on the grounding electrode side. CONSTITUTION:A mesh electrode 10 having many gaseous reactant passage holes 10a and having the grounded potential is arranged in a reaction chamber 1 between an RF electrode 5 to be impressed with a high-frequency power and an electrically insulated substrate 17 outside the sheath region of the plasma produced from the electrode 5, and an inlet pipe 6 is provided to feed a gaseous reactant to the electrode 5. Consequently, the gaseous reactant which has passed through the sheath region on the grounding electrode side and with the potential lowered by the mesh electrode is allowed to react with the substrate, and the ion does not impinge on the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention excites and decomposes a reaction gas by glow discharge to cause a reaction in a low temperature region of a substrate to deposit a film, for example, Si ₃ N ₄ or SiO _{2 on} the surface of the substrate. The present invention relates to a plasma CVD apparatus that forms an insulating film and a protective film.

[0002]

2. Description of the Related Art A conventional capacitively coupled plasma CVD apparatus.
Are parallel to each other in the reaction chamber 21 as shown in FIG.
A high frequency is applied to the flat plate 22 to cause discharge, and the reaction gas
Reaction gas (SiH_Four＋ NH₃, Si
H_Four＋ N₂(For example, O) to excite and ionize the
Creates separated ions and highly reactive neutral molecules. So
Then, the reaction gas is arranged in parallel below the flat plate 22.
Heated by the heater 25 on the ground electrode 24
Reacting on the surface of the substrate 26_XN_YAnd SiO _xSuch
The insulating thin film is deposited and formed.

[0003]

However, in the above structure, the substrate 26 is usually disposed on the ground electrode 24 to form a thin film, and there is a sheath region where the potential drops on the side of the flat plate 22. At the same time, there is a sheath region where the potential drops on the ground electrode 24 side. Then, the positive ions are accelerated by the electric field in this sheath region and the ground electrode 2
There is a problem in that ion collisions that collide with the surface of the substrate 26 on the No. 4 substrate occur, which adversely affects the formation of the thin film.

The present invention solves the above problems and prevents the ion collision with the substrate caused by the sheath electric field on the side of the ground electrode, thereby improving the film quality.
The purpose is to provide a device.

[0005]

In order to solve the above problems, the first plasma CVD apparatus of the present invention is electrically insulated from the plasma generating electrode to which a high frequency or microwave is applied in the reaction chamber. A mesh electrode having a large number of reaction gas passage holes formed therein and having a ground potential is arranged outside the sheath region of the generated plasma between the substrate and the reaction gas for supplying the reaction gas in the vicinity of the plasma generation electrode. A supply pipe is provided.

In the second plasma CVD apparatus, a plasma chamber formed of an insulator and having one end face opened is provided in the reaction chamber, and a high frequency or microwave is applied to the other end side of the plasma chamber. In addition to disposing the generation electrode, a reaction gas supply pipe for supplying a reaction gas is provided in the plasma chamber, and the one end surface opening portion of the plasma chamber is disposed outside the sheath region of the plasma generated from the plasma generation electrode to cover the plasma chamber. In addition, a mesh electrode having a large number of reaction gas passage holes formed therein and having a ground potential is provided, and an electrically insulated substrate is provided outside the plasma chamber so as to face the mesh electrode.

[0007]

In the above structure, the potential distribution between the plasma generating electrode and the mesh electrode has a sheath region where the potential drops in a predetermined range on the plasma generating electrode side and a predetermined range on the mesh electrode side, respectively, and electrons are accelerated in this region. Electrons that have become highly energized cause various reactions. Therefore, the active gas molecules that have reached the substrate through the reaction gas passage holes of the mesh electrode cause a surface reaction outside the sheath region to deposit and form a thin film on the substrate. It is possible to improve the film quality of the thin film without causing the phenomenon.

Further, by reliably containing the high-potential and high-energy plasma in the plasma chamber, the potential in the plasma chamber can be increased and the uniformity can be improved, and the gas reaction can be efficiently generated. It is possible to suppress the reaction to the inner wall of the reaction chamber, reduce the adhered particles and the film formation, and reduce the cleaning and maintenance.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the plasma CVD apparatus according to the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 is a reaction chamber formed by a reaction vessel 2 which is set to ground potential, and a plasma chamber 4 formed by an insulator 3 and having an open lower surface is formed in an upper portion of the reaction chamber 1. Has been done. An RF electrode (which may be a high-frequency electrode or a microwave discharge electrode) 5 is arranged above the plasma chamber 4, and a gas inflow chamber 7 is formed in the RF electrode 5 to form a reaction gas. A gas inflow pipe 6 for supplying a reaction gas from a supply device (not shown) penetrates the reaction vessel 2 via an insulator 3 and is connected to a gas inflow chamber 7 of the RF electrode 5, and a large number of them are provided on the lower surface of the RF electrode 5. The reaction gas is ejected into the plasma chamber 4 through the ejection hole 5a that is formed and communicates with the gas inflow chamber 7. Also this R
High frequency power is applied to the F electrode 5 from the high frequency power supply 8 through the matching circuit 9 and the gas inflow pipe 6.

A large number of reaction gas passage holes 10a are formed in the open portion of the lower surface of the plasma chamber 4 outside the sheath region of the RF electrode 5.
The plate-shaped mesh electrode 10 on which is formed the mounting member 1
1, the plasma chamber 4 is covered and the excited and ionized reactive gas in the plasma chamber 4 is supplied to the reaction gas passage hole 10a of the mesh electrode 10.
It is configured to be supplied into the reaction chamber 1 only via the. The mesh electrode 10 is connected to the reaction container 2 via the conductor 12 and the mounting member 11 and is set to the ground potential.

At the bottom of the reaction chamber 1, a substrate table 15 having a heater 14 built in on an insulating plate 13 is arranged. This substrate table 15 is connected to the reaction vessel 2 via a conductor 16 and is set to the ground potential. While being held, the substrate 17 is placed on the substrate table 15. An exhaust pipe 19 connected to an exhaust pump (not shown) is connected to the bottom of the reaction chamber 1. Reference numeral 18 is a heater control power supply for the heater 14.

FIG. 2 shows an average potential distribution in the discharge region between the RF electrode 5 and the mesh electrode 10. The potential of this discharge region is always kept at the plasma potential V _P higher than the ground potential. In the figure, the solid line A shows the case where the plasma is contained as in the embodiment, and the broken line B shows the case where the periphery between the RF electrode 5 and the mesh electrode 10 is opened. The plasma potential V _P when the plasma is contained is higher and more uniform than the plasma potential V _P ′ when the plasma is not contained. That is, the efficiency of plasma energy with respect to the high frequency power of the RF electrode 5 is high, and the gas can be efficiently reacted. Here, V _DC is the self-bias voltage, V _S
Is the voltage applied to the RF electrode 5.

Further, the RF electrode 5 and the mesh electrode 10
The potential drop that occurs in the vicinity is in the sheath regions C ₁ and C ₂ , and a strong electric field is formed. In the sheath regions C ₁ and C ₂ , the electrons are accelerated and the highly energized electrons cause various reactions. Further, so-called ion collision occurs in which the positive ions are accelerated by the sheath electric field and bombard the electrodes. This ion collision also occurs on the side of the ground electrode (mesh electrode 10), and when a film is deposited and formed on the surface of the substrate on the ground electrode as in the conventional case, the ion collision has a bad influence on the film formation. . However, in this embodiment, the ion collision can be avoided by disposing the substrate 17 at a position apart from the ground electrode (mesh electrode 10).

In the above structure, the high frequency power source 8 drives the RF
A high frequency is applied to the electrode 5 to cause discharge and
The reaction gas serving as a material is ejected from the ejection hole 5a of the RF electrode 5.
The plastic chamber 4 that is enclosed in a plasma chamber 4
Reaction gas (SiH_Four＋ NH ₃, SiH_Four＋ N₂Encourage (O, etc.)
Ions generated and ionized and ionized in plasma
Create a highly reactive neutral molecule and add this reactive gas to
Reaction gas passage hole 10a of the mesh electrode 10 from the chamber 4
It is carried to the substrate 17 via the heater and heated by the heater 14.
React on the surface of the heated substrate 17 to produce Si_XN_YAnd SiO
_xAn insulating thin film such as is deposited and formed. Therefore, RF
Electrode 5 to sheath region C₁Earth power supply placed outside
The substrate 17 at a position distant from the mesh electrode 10 at the upper position
By doing so, it is possible to avoid ion collision and
High quality thin films can be deposited. Moreover, Plas
Since the plasma was enclosed in the chamber 4, the plasma potential V
_PThe RF electrode 5 has a high height and high uniformity.
Improves the efficiency of plasma energy with respect to frequency power
The gas can be reacted efficiently.

[0016]

As described above, the plasma C of the present invention is used.
According to the VD device, the potential distribution between the plasma generating electrode and the mesh electrode has a sheath region where the potential drops in a predetermined range on the plasma generating electrode side and a predetermined range on the mesh electrode side, respectively, and electrons are accelerated in this region. The energized electrons cause various reactions to cause ion collision with positive ions. Therefore, the gas molecules reaching the substrate through the reaction gas passage holes of the mesh electrode cause a surface reaction on the substrate outside the sheath region to form a thin film on the substrate, and thus the substrate is grounded as in the conventional case. Compared with the above, the film quality of the thin film can be improved without causing the ion collision by the positive ions.

Further, by reliably confining the high-potential, high-energy plasma in the plasma chamber, the potential of the discharge region in the plasma chamber can be increased and the uniformity can be improved, and the gas can be efficiently excited and ionized. It is possible to deposit and form a thin film by using the above method, and to suppress the reaction to the inner wall of the reaction chamber to reduce the adhered particles and the film formation, thereby reducing the cleaning and maintenance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a plasma CVD apparatus according to the present invention.

FIG. 2 is a graph showing an average potential distribution in a discharge region in the plasma CVD apparatus.

FIG. 3 is a sectional view showing a conventional plasma CVD apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Reaction container 3 Insulator 4 Plasma chamber 5 RF electrode 5a Jet hole 6 Gas inflow pipe 7 Gas inflow chamber 8 High frequency power supply 10 Mesh electrode 10a Reaction gas passage hole 11 Mounting member 12 Conductor 13 Insulating plate 14 Heating heater 15 Substrate Table 17 Substrate C ₁ , C ₂ Sheath area V _P Plasma potential

Claims (2)

[Claims] 1. A large number of reaction gas passage holes are formed outside a sheath region of plasma generated in a reaction chamber between a plasma generation electrode to which a high frequency or microwave is applied and an electrically insulated substrate. A plasma CVD apparatus characterized in that a mesh electrode which is grounded to a ground potential is arranged, and a reaction gas supply pipe for supplying a reaction gas is provided in the vicinity of the plasma generating electrode. 2. A plasma chamber formed of an insulator and having one end surface opened is provided in the reaction chamber, and a plasma generating electrode to which a high frequency or a microwave is applied is disposed on the other end side of the plasma chamber, A reaction gas supply pipe for supplying a reaction gas is provided in the plasma chamber, and the one end surface opening portion of the plasma chamber is arranged outside the sheath region of the plasma generated from the plasma generating electrode to cover the plasma chamber and a large number of reaction gas passage holes. The plasma CVD apparatus is characterized in that a mesh electrode is formed to have a ground potential and an electrically insulated substrate is provided outside the plasma chamber so as to face the mesh electrode.